The goal is to develop reagents and methods for the direct chemical synthesis of fluorescent DNAs destined for use as DNA hybridization probes and in primer directed DNA sequencing. Recently, Hood and coworkers have developed a primer directed DNA sequencing technique. DNA probes have also been found to be useful for detecting bacteria and viruses as well as genetic abnormalities. Several companies are currently developing direct fluorescent probes for use in such applications with the ultimate goal of producing rapid, sensitive and reliable clinical tests. Currently, most synthetic procedures for making fluorescent DNA probes rely on secondary enzymatic and chemical modification. These developments would be speeded by the introduction of methods for direct synthesis of the desired product. In Phase i we propose to synthesize novel fluorescent labeled nucleotide phosphoramidites suitable for use in automated DNA synthesizers. These compounds will be used to synthesize the fluorescent oligonucleotides. The general availability of such compounds should significantly stimulate progress in the use of fluorescent probes as non-isotopic diagnostic and sequencing reagents.